Robot joint speed reducer device and working method

Abstract

The invention provides a robot joint speed reducer device and a working method, relates to the field of joint speed reducers, and aims at solving the problem that an existing robot speed reducer cannot meet the requirement for a large speed reduction ratio and meanwhile achieve high-rigidity transmission and clearance compensation, three speed reduction transmissions connected in series are constructed, and the speed reduction ratio is effectively increased. Through a helical tooth planetary gear structure of three-stage speed reduction transmission, a return clearance of three-stage speed reduction transmission is eliminated, and two driving elements are utilized to apply reverse torque to a second-stage driven gear through a second-stage driving gear, so that the return clearance of first-stage speed reduction transmission and the return clearance of second-stage speed reduction transmission are effectively eliminated; and the rigidity of the whole speed reducer is enhanced through helical gear transmission combined with three-stage speed reduction transmission, and the working performance and reliability of the robot are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of joint reducers, and particularly to a robot joint reducer device and a working method thereof. Background Art

[0002] Industrial robot joints usually use high-precision reducers in combination with servo motors to achieve power transmission, and their design focuses on the core goals of high stiffness and high load capacity. However, mechanical damages such as wear on the gear meshing surface and expansion of bearing clearance caused by long-term operation will generate backlash, resulting in an idle rotation angle difference between the input shaft and the output shaft of the transmission system, which directly affects the repeat positioning accuracy of the robot. In high-speed commutation or precision assembly scenarios, the vibration and error accumulation caused by the clearance will seriously affect the accuracy and reliability of the robot. There are currently many studies on the clearance elimination technology for robot joint reducers, mainly including various methods such as mechanical preloading method, sensor compensation method, variable stiffness structure, etc. Among them, the mechanical preloading method reduces the clearance by adjusting the gear preloading force, but excessive preloading force will increase the friction loss and reduce the transmission efficiency, and it cannot dynamically adapt to wear changes; the sensor compensation method uses an encoder to monitor the clearance and compensates the error through a control algorithm, but this method relies on high-precision sensors and complex control models, with high costs and limited real-time performance, and it is difficult to cope with sudden load changes; the variable stiffness structure relies on, such as a permanent magnet spring, to reconstruct the joint, and changes the joint stiffness by adjusting mechanical variables, but its dynamic response speed is slow, and it is difficult to balance the requirements of high stiffness and low energy consumption.

[0003] Chinese Patent (Publication No. CN114877032A, Publication Date: August 9, 2022) discloses a large torque and high rigidity robot joint reducer. The left and right gears in the planetary triple gears are simultaneously meshed with the double-row sun gear arranged on the input shaft and the internal gear ring embedded in the left and right connecting plates to achieve primary transmission, and the middle gear of the planetary triple gears is meshed with the output gear ring to achieve secondary transmission; making the transmission structure compact and the transmission efficiency high, but it still has the problem of relatively large gear backlash in the return stroke meshing, and the reduction ratio of its adopted secondary reduction transmission is difficult to meet the requirements, and it is difficult to balance the requirements of a large reduction ratio while achieving high stiffness transmission and clearance compensation. Summary of the Invention

[0004] The purpose of the present invention is to address the defects existing in the prior art, and provide a robot joint reducer device and a working method thereof, which construct three series-connected reduction transmissions, effectively increase the reduction ratio, eliminate the backlash in the return stroke of the three-stage reduction transmission through the helical planetary gear structure of the three-stage reduction transmission, and use two driving elements to apply reverse torques to the secondary driven gear through the secondary driving gear, not only effectively eliminating the backlash in the return stroke of the primary reduction transmission and the secondary reduction transmission, but also enhancing the stiffness of the entire reducer by combining the helical gear transmission of the three-stage reduction transmission, and significantly improving the working performance and reliability of the robot.

[0005] The first object of the present invention is to provide a robot joint speed reducer device, which adopts the following scheme:

[0006] Including:

[0007] Three-stage reduction drive, which is a helical planetary gear structure. Two sets of planetary gear sets with opposite helix directions are installed on the planet carrier and respectively mesh with the sun helical gear shafts. An axial elastic mechanism is provided at the end of the sun helical gear shafts to apply an axial elastic pre-tightening force to the sun helical gear shafts, eliminating the backlash of the three-stage reduction drive; the planet carrier is connected with a follower cover as the output end;

[0008] Two-stage reduction drive, including a two-stage driven gear and a two-stage driving gear. The two-stage driven gear is installed on the sun helical gear shaft and rotates at a constant angular velocity, and two two-stage driving gears respectively mesh with the two-stage driven gear;

[0009] One-stage reduction drive, with two sets provided to cooperate with the two two-stage driving gears. Each set of one-stage reduction drive includes a meshing one-stage driving bevel gear and one-stage driven bevel gear. The one-stage driven bevel gear rotates at the same angular velocity coaxially with the two-stage driving gear, and the one-stage driving bevel gear is connected to the driving element; the two driving elements apply reverse torques to the two-stage driven gear through the two-stage driving gears, eliminating the backlash of the one-stage reduction drive and the two-stage reduction drive.

[0010] Further, the one-stage driving bevel gear is a hyperbolic spiral bevel gear shaft, the one-stage driven bevel gear is an end face spiral bevel gear, and the driving element is located outside one end of the two-stage driven gear and is distributed obliquely to the axis of the sun helical gear shaft.

[0011] Further, the two two-stage driving gears are symmetrically arranged with respect to the axis of the sun helical gear shaft.

[0012] Further, the axes of the one-stage driving bevel gears connected by the two driving elements are parallelly distributed, and the axes of the one-stage driving bevel gear and the one-stage driven bevel gear in the same group are perpendicular.

[0013] Further, the three-stage reduction drive further includes an external gear ring cooperating with the planetary gear sets. The external gear ring is connected with an end cover. One end of the sun helical gear shaft is rotatably fitted with the end cover, and the other end is rotatably fitted with the follower cover. An axial movement allowance is left between the sun helical gear shaft and the planetary gear sets.

[0014] Further, the axial elastic mechanism includes an axial sliding block, a wave spring and a pre-tightening screw cap. The sun helical gear shaft is fitted with the end cover through a tapered roller bearing I. The axial sliding block abuts against the outer ring of the tapered roller bearing I. The pre-tightening screw cap cooperates with the end cover, and the wave spring abuts between the pre-tightening screw cap and the axial sliding block.

[0015] Further, the planet carrier includes a transmission shaft, and the planetary gear set is mounted on the transmission shaft and meshes with the external gear ring.

[0016] Further, the planet carrier further includes a first planet carrier and a second planet carrier that are axially spaced along the sun helical gear shaft. One set of planetary gear sets is located between the first planet carrier and the second planet carrier, and the other set of planetary gear sets is located between the second planet carrier and the follower cover.

[0017] The second object of the present invention is to provide a working method of a robot joint reducer device as described in the first object, including:

[0018] The follower cover is connected to an external actuator.

[0019] During movement, one driving element serves as the main driving element to output a positive driving torque, and the other driving element serves as the auxiliary driving element to output a reverse torque, and the reverse torque is less than the positive driving torque, so as to keep the reverse tooth surfaces of the first-stage driven bevel gear and the first-stage driving bevel gear engaged, and at the same time ensure that the reverse tooth surfaces of the second-stage driving gear and the second-stage driven gear are engaged, eliminating the backlash of the first-stage and second-stage speed reduction transmissions.

[0020] The sun helical gear shaft generates an axial displacement, driving two sets of planetary gear sets with opposite helix directions to rotate in opposite angles, so that the sun helical gears on the sun helical gear shaft respectively press against the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the backlash of the third-stage speed reduction transmission.

[0021] The driving element drives the follower cover to output power after passing through the first-stage, second-stage, and third-stage speed reduction transmissions in sequence.

[0022] Further, adjust the pre-tightening force of the axial elastic mechanism so that the sun helical gear shaft can simultaneously engage with the opposite tooth surfaces of the two sets of planetary gear sets.

[0023] Compared with the prior art, the advantages and positive effects of the present invention are:

[0024] Aiming at the problem that the current robot reducer is difficult to meet the demand for large reduction ratio and realize high stiffness transmission and clearance compensation at the same time, three series reduction transmissions are constructed to effectively increase the reduction ratio. Through the helical planetary gear structure of the three-stage reduction transmission, two sets of planetary gear sets with opposite rotation directions are installed on the planet carrier. Combined with the axial elastic mechanism matched at the end of the sun helical gear shaft, an axial elastic preload can be applied to the sun helical gear shaft. The preload can keep the two sets of planetary gear sets in close contact during the forward and reverse transmission processes, thereby eliminating the return clearance of the three-stage reduction transmission and improving the transmission accuracy and stability. Two driving elements are used to apply reverse torque to the secondary driven gear through the secondary driving gear, which not only realizes the effective elimination of the return clearance of the primary reduction transmission and the secondary reduction transmission, but also enhances the stiffness of the entire reducer in combination with the helical gear transmission of the three-stage reduction transmission. When the robot joint is subjected to a large load, the reducer can effectively resist deformation and vibration with its high stiffness characteristics to ensure the stable operation of the robot. The torque output is increased by using multi-stage reduction transmission, which significantly improves the working performance and reliability of the robot and prolongs its service life.

[0025] Among them, the three-stage reduction transmission adopts a bidirectional planetary helical gear synchronous parallel transmission. By applying axial static preload force to the sun helical gear shaft, a difference in the meshing angle of the planetary gears is formed, thereby eliminating the bidirectional tooth surface clearance of the planetary gear set, so that the robot joint can meet the requirements of a large reduction ratio while achieving high-rigidity transmission and clearance compensation.

[0026] The overall compact design meets the requirements of narrow space layout of robot joints. The first-stage reduction transmission adopts bevel gear transmission. The first-stage active bevel gear is a hyperbolic spiral bevel gear shaft, and the first-stage driven bevel gear is an end face spiral bevel gear. The axis is vertical, and the torque is transmitted by the hyperbolic spiral bevel gear structure. At the same time, the driving element is biased towards the axis of the sun helical gear shaft, which reduces the axial and radial dimensions of the reducer and prevents interference during the operation of the robot. The use of wave springs can reduce the axial dimension compared to traditional compression springs.

[0027] The sun helical gear shaft in the reducer is subjected to axial preload through a corrugated spring. Combined with the adjustable clearance of the tapered roller bearing, it can dynamically compensate for the enlarged clearance caused by tooth surface wear, thereby improving the working stability of the robot joint reducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 An exploded view of a robot joint reducer device in one or more embodiments of the present invention.

[0030] Figure 2 Schematic assembly diagram of the robot joint speed reducer device in one or more embodiments of the present invention.

[0031] Figure 3 Internal gear structure diagram of the robot joint speed reducer device in one or more embodiments of the present invention.

[0032] Figure 4 Exploded view of the left-handed planetary gear set of the robot joint speed reducer device in one or more embodiments of the present invention.

[0033] Figure 5 Exploded view of the right-handed planetary gear set of the robot joint speed reducer device in one or more embodiments of the present invention.

[0034] Figure 6 Exploded view of the second planet carrier of the robot joint speed reducer device in one or more embodiments of the present invention.

[0035] Figure 7 Transmission schematic diagram of the robot joint speed reducer device in one or more embodiments of the present invention.

[0036] Wherein, 1, hyperbolic spiral bevel gear shaft; 2, end face spiral bevel gear; 3, pre-tightening bolt; 4, servo motor; 5, straight-tooth large gear; 6, straight-tooth gear shaft; 7, sun helical gear shaft; 8, left-handed planetary gear set; 9, right-handed planetary gear set; 10, transmission shaft; 11, external gear ring; 12, deep groove ball bearing II; 13, deep groove ball bearing III; 14, sleeve I; 15, tapered roller bearing I; 16, tapered roller bearing II; 17, sleeve II; 18, first planet carrier; 19, tapered roller bearing III; 20, deep groove ball bearing IV; 21, second planet carrier; 22, follower cover; 23, deep groove ball bearing VI; 24, shaft retaining ring II; 25, rotary seal I; 26, hole retaining ring II; 27, tapered roller bearing IV; 28, rotary seal II; 29, hole retaining ring III; 30, end cover I; 31, bolt I; 32, O-ring I; 33, axial sliding block; 34, wave spring; 35, pre-tightening screw cap; 36, end cover II; 37, bolt II; 38, O-ring II; 39, bolt III; 40, O-ring III; 211, planet carrier; 212, deep groove ball bearing V; 213, hole retaining ring I; 801, left-handed planetary gear; 802, deep groove ball bearing I; 901, right-handed planetary gear. Detailed implementation manners

[0037] Embodiment 1

[0038] In a typical embodiment of the present invention, as Figures 1-7 shown, a robot joint speed reducer device is provided.

[0039] The current large-torque and high-rigidity robot joint reducers have the advantages of a compact transmission structure and high transmission efficiency. However, they have a relatively large backlash in gear meshing during return, which affects the transmission accuracy and stability. In some robot application scenarios with extremely high precision requirements, the large backlash can cause problems such as positioning deviation during the movement of the robot. Moreover, the two-stage reduction transmission method they adopt has limitations in terms of reduction ratio and is difficult to meet the requirements of a large reduction ratio. In cases where a high reduction ratio is needed to achieve low-speed and high-torque output, it is impossible to simultaneously achieve high-rigidity transmission and backlash compensation, resulting in situations where the robot joints are prone to deformation, vibration, etc. under heavy loads, seriously affecting the working performance and service life of the robot. Based on this, this embodiment provides a robot joint reduction device that constructs three series-connected reduction transmissions, effectively increasing the reduction ratio. Through the helical planetary gear structure of the three-stage reduction transmission, the backlash of the three-stage reduction transmission is eliminated. By using two drive elements to apply reverse torque to the secondary driven gear through the secondary driving gears, not only is the backlash of the first-stage and second-stage reduction transmissions effectively eliminated, but also the rigidity of the entire reducer is enhanced by combining the helical gear transmission of the three-stage reduction transmission, significantly improving the working performance and reliability of the robot.

[0040] Specifically, as Figures 1-3 shown, the robot joint reducer device includes a first-stage reduction transmission, a second-stage reduction transmission, and a third-stage reduction transmission connected in series in sequence. The first-stage reduction transmission uses a bevel gear structure with a 90° vertical distribution for transmission, meeting the requirements of reduction transmission and facilitating the position allocation of the drive element serving as the power input, reducing the occupied space. The second-stage reduction transmission uses spur gear transmission. One secondary driven gear meshes with two secondary driving gears, and reverse torque is input to achieve the effect of eliminating backlash. The third-stage reduction transmission uses a planetary gear reduction mechanism, which is a helical planetary gear structure. Two sets of planetary gear sets are combined with a sun helical gear shaft 7 with an axial elastic mechanism to achieve the axial sliding of the sun helical gear shaft 7 and maintain the positive and reverse tight transmission between the sun helical gear shaft 7 and the planetary gear sets.

[0041] As Figure 3 shown, the third-stage reduction transmission is a helical planetary gear structure. Two sets of planetary gear sets with opposite helix directions are installed on the planet carrier 211 and respectively mesh with the sun helical gear shaft 7. The end of the sun helical gear shaft 7 is equipped with an axial elastic mechanism to apply an axial elastic pre-tightening force to the sun helical gear shaft 7 to eliminate the backlash of the third-stage reduction transmission. The planet carrier 211 is connected with a follower cover 22 as the output end;

[0042] As Figure 2 shown, the second-stage reduction transmission includes a secondary driven gear and secondary driving gears. The secondary driven gear is installed on the sun helical gear shaft 7 and rotates at a constant angular velocity. The two secondary driving gears respectively mesh with the secondary driven gear;

[0043] like Figure 1 and Figure 2 As shown, the primary reduction transmission is provided with two groups of matched two secondary driving gears, each group of the primary reduction transmission includes a meshing primary driving bevel gear and a primary driven bevel gear, the primary driven bevel gear and the secondary driving gear rotate coaxially with the same angular velocity, and the primary driving bevel gear is connected to the driving element; the two driving elements apply reverse torque to the secondary driven gear through the secondary driving gear to eliminate the return clearance between the primary reduction transmission and the secondary reduction transmission.

[0044] The two driving elements drive two groups of primary driving bevel gears to rotate respectively, and the primary driving bevel gear drives the primary driven bevel gear meshed therewith to rotate. The primary driven bevel gear is coaxial with the secondary driving gear, so the power is transmitted to the secondary driving gear. The two driving elements apply reverse torque to the secondary driven gear through the secondary driving gear, and realize backlash compensation while transmitting power. The two secondary driving gears are respectively meshed with the secondary driven gears, and the power from the primary reduction transmission is transmitted to the secondary driven gears. Due to the different gear ratios between the secondary driving gears and the secondary driven gears, secondary reduction is realized. The secondary driven gear drives the sun bevel gear shaft 7 to rotate, and the input power is transmitted through the sun bevel gear shaft 7. The sun bevel gear shaft 7 drives two sets of planetary gear sets with opposite rotation directions to rotate around their own axes, and at the same time, the planetary gear sets revolve around the sun bevel gear shaft 7 under the constraint of the planet carrier 211. Due to the gear ratio between the planetary gear set and the sun bevel gear shaft 7 and the motion relationship between the planet carrier 211 and the planetary gear set, reduction is realized. The follower cover 22 connected to the planet carrier 211 is used as the output end to output the power after three-stage reduction.

[0045] like Figure 7 As shown in the figure, through the cooperation of three-stage reduction transmission, two-stage reduction transmission and one-stage reduction transmission, multi-stage reduction significantly increases the reduction ratio. Gear transmissions of different levels can convert input high-speed power into output low-speed and high-torque power through reasonable matching of the number of teeth, meeting the robot joint's demand for a large reduction ratio, so that the robot can achieve more accurate and stable low-speed movement when working.

[0046] like Figure 3 As shown, for the first-stage reduction transmission, the axes of the first-stage active bevel gears connected to the two driving elements are parallel, the axes of the first-stage active bevel gears and the first-stage driven bevel gears in the same group are perpendicular, the first-stage active bevel gear is a hyperbolic spiral bevel gear shaft 1, and the first-stage driven bevel gear is an end face spiral bevel gear 2. Specifically, both groups of first-stage reduction transmissions adopt a 90° vertical transmission, a hyperbolic spiral bevel gear is formed on the hyperbolic spiral bevel gear shaft 1, and the driving element adopts a servo motor 4. The driving element is located outside one end of the second-stage driven gear and is distributed toward the axis of the sun bevel gear shaft 7, as shown in FIG. Figure 3As shown, the two secondary driving gears are arranged symmetrically relative to the axis of the sun bevel gear shaft 7, and the two driving elements are also arranged symmetrically.

[0047] It should be noted that a compact structure is adopted to meet the requirements of narrow space layout of robot joints. The first-stage reduction transmission adopts bevel gear transmission with a vertical axis, which reduces the axial space along the sun bevel gear shaft 7. The driving element is distributed toward the axis of the sun bevel gear shaft 7, which reduces the space occupied by the driving element to the outside, reduces the axial size and radial size of the reducer, and prevents interference during the operation of the robot.

[0048] In this embodiment, a coupling hole is provided at the end of the hyperbolic spiral bevel gear shaft 1, and the servo motor 44 is fastened and connected by the pre-tightening bolt 3. The input torque of the two servo motors 4 is respectively transmitted from the two hyperbolic spiral bevel gear shafts 1 to the end spiral bevel gear 2. During operation, one of the servo motors 4 is used as the main motor to output the positive driving torque, and the other servo motor 4 is used as the auxiliary motor to apply a small reverse torque to ensure the reverse tooth surface engagement, thereby eliminating the return clearance of the first-stage reduction transmission, and the output direction of the joint torque can be changed by switching the main driving force source.

[0049] like Figure 2 and Figure 3 As shown, for the secondary reduction transmission, the secondary driven gear is a spur gear 5, the secondary driving gear is a spur pinion, the spur pinion is distributed on the spur gear shaft 6, one spur gear 5 and two spur gear shafts 6 are meshed in opposite directions, and the end face spiral bevel gear 2 is connected to the spur gear shaft 6 through a flat key interference fit, so that the primary driven bevel gear and the secondary driving gear rotate coaxially with the same angular velocity. The input torque of the two end face spiral bevel gears 2 is transmitted from the spur gear shaft 6 to the spur gear 5. Since the input torque is in opposite directions, it can be ensured that the spur gear shaft 6 always has a tooth surface that fits the spur gear 5 during reversing, eliminating the return clearance of the secondary reduction transmission.

[0050] like Figure 1 , Figure 2 and Figure 3 As shown, the three-stage reduction transmission also includes an outer ring gear 11 that cooperates with the planetary gear set. The outer ring gear 11 is connected to an end cover. One end of the sun bevel gear shaft 7 rotates to cooperate with the end cover, and the other end rotates to cooperate with the follower cover 22. An axial movement allowance is left between the sun bevel gear shaft 7 and the planetary gear set.

[0051] Specifically, the three-stage reduction transmission adopts a helical planetary gear structure. Two sun helical gears are formed on the sun helical gear shaft 7, which respectively mesh with two sets of planetary gear sets, one of which is a left-handed planetary gear set 8 and the other is a right-handed planetary gear set 9. Figure 3As shown, each set of planetary gear sets includes three planetary gears. The left-handed planetary gear set 8 includes three left-handed planetary gears 801, which are circumferentially evenly distributed along the sun helical gear shaft 7 and mesh with the same sun helical gear. The right-handed planetary gear set 9 includes three right-handed planetary gears 901, which are circumferentially evenly distributed along the sun helical gear shaft 7 and mesh with the same sun helical gear. The left-handed planetary gears 801 and the right-handed planetary gears 901 are fitted with a transmission shaft 10 and are installed on the planet carrier 211 through the transmission shaft 10. The planetary gears mesh with the outer gear ring 11.

[0052] Specifically, the sun helical gear shaft 7 and the straight-tooth large gear 5 are connected by interference fit with involute splines. Left-handed helical teeth and right-handed helical teeth with spaced axes are machined on the outer circumferential surface of the sun helical gear shaft 7 to form the sun helical gears that mesh with the planetary gear sets respectively. The left-handed planetary gear set 8 and the right-handed planetary gear set 9 are installed on the transmission shaft 10 according to the helical tooth directions on the outer surface of the sun helical gear shaft 7. Left-handed helical teeth and right-handed helical teeth are machined on the inner surface of the outer gear ring 11 according to the helical tooth directions of the sun helical gear shaft 7. The left-handed planetary gears 801 and the right-handed planetary gears 901 cooperate with the same transmission shaft 10, and the three left-handed planetary gears 801 respectively correspond to the three transmission shafts 10.

[0053] The planet carrier one 18 and the planet carrier two 21 that are axially spaced along the sun helical gear shaft 7, where the left-handed planetary gear set 8 is located between the planet carrier one 18 and the planet carrier two 21, and the right-handed planetary gear set 9 is located between the planet carrier two 21 and the follower cover 22.

[0054] The torque input by the straight-tooth large gear 5 is transmitted from the sun helical gear shaft 7 to the two sets of planetary gear sets. Due to the parallel output of two sets of reverse planetary helical gears, an axial micro-displacement is generated through the sun helical gear shaft 7, driving the left-handed planetary gear set 8 and the right-handed planetary gear set 9 to rotate in opposite small angles, so that the two gears are respectively pressed against the opposite tooth surfaces on the sun helical gear shaft 77, thereby eliminating the return clearance of the three-stage reduction drive.

[0055] Specifically, in the secondary reduction drive, a deep groove ball bearing two 12 is arranged at the top end of the straight-tooth gear shaft 6, and a deep groove ball bearing three 13 is arranged at the bottom end. Among them, a shaft sleeve one 14 is arranged between the inner ring of the deep groove ball bearing two 12 and the axial end face spiral bevel gear 2 for axial limit, and the inner ring of the deep groove ball bearing three 13 is axially limited by the shoulder of the straight-tooth gear shaft 6.

[0056] Specifically, in the tertiary reduction drive, a tapered roller bearing one 15 is arranged at the top end of the sun helical gear shaft 7, and a tapered roller bearing two 16 is arranged at the bottom end. To ensure the smooth axial transmission of the sun helical gear shaft 7, the tapered roller bearing one 15 and the tapered roller bearing two 16 are installed face to face. Among them, a shaft sleeve two 17 is arranged between the inner ring of the tapered roller bearing one 15 and the straight-tooth large gear 5 for axial limit, and the inner ring of the tapered roller bearing two 16 is axially limited by the shoulder of the sun helical gear shaft 7.

[0057] As Figure 4 and Figure 5 shown, the left-handed planetary gear set 8 includes a left-handed planetary gear 801 and two deep groove ball bearings 802. A bearing seat is provided in the middle of the inner ring of the left-handed planetary gear 801. The outer rings of the two deep groove ball bearings 802 are axially positioned with an interference fit with the left-handed planetary gear 801 and are oppositely installed in the bearing seat; the right-handed planetary gear set 9 includes a right-handed planetary gear 901 and two deep groove ball bearings 802, and the installation method is the same as that of the left-handed planetary gear set 8.

[0058] As Figure 1 、 Figure 2 、 Figure 3 and Figure 6 shown, to support the uniform and stable operation of the planetary gear set, a first planet carrier 18 is provided between the spur gear 5 and the left-handed planetary gear set 8. A bearing seat hole is machined in the center of the first planet carrier 18, and three planetary bearing seat holes are machined and evenly distributed circumferentially. The center bearing seat hole and the spur gear 5 are supported and rotated by a third tapered roller bearing 19 in a face-to-face installation. The third tapered roller bearing 19 and the first tapered roller bearing 15 are installed face to face. The planetary bearing seat hole and the transmission shaft 10 are supported and transmitted by a fourth deep groove ball bearing 20; at the same time, to further enhance the operation stability of the planetary gear set and reduce the vibration during power transmission, a second planet carrier 21 is provided between the left-handed planetary gear set 8 and the right-handed planetary gear set 9. Among them, a relief hole is machined in the center of the second planet carrier 21, and three planetary bearing seat holes are machined and evenly distributed circumferentially. A fifth deep groove ball bearing 212 is provided in the planetary bearing hole to support the rotation, and is axially limited by a first retaining ring for hole 213. The transmission shaft 10 passes through the inner ring of the fifth deep groove ball bearing 212 and is axially limited by a shaft shoulder.

[0059] Specifically, a follower cover 22 is provided at the end of the transmission shaft 10 to output the torque of the reducer. Three bearing seat holes are evenly arranged axially on the follower cover 22 to install the sixth deep groove ball bearing 23 to support the rotation of the three transmission shafts 10. The inner ring of the bearing is axially limited by a second retaining ring for shaft 24. To enhance the sealing performance of the reducer and prevent external dust and impurities from entering the interior of the reducer, a first rotary seal 25 is provided between the follower cover 22 and the transmission shaft 10 and is axially limited by a second retaining ring for hole 26. And a bearing seat hole is opened in the center of the follower cover 22 to install a second tapered roller bearing 16 to support the rotation of the sun helical gear shaft 7. Threaded holes are evenly opened circumferentially on the surface of the follower cover 22 and are connected to the load end of the robot joint by cooperating with fasteners. The number and size of the threaded holes are opened according to requirements, and no further requirements are made in this embodiment.

[0060] Specifically, cylindrical rollers are arranged between the follower cover 22 and the external gear ring 11. Taking the follower cover 22 as the inner ring of the bearing and the external gear ring 11 as the outer ring of the bearing, a tapered roller bearing four 27 is constructed to support the transmission. The tapered roller bearing four 27 is composed of cylindrical rollers and a cage. The contact surface between the follower cover 22 and the external gear ring 11 is processed into a conical surface according to the requirements of the bearing roller raceway to serve as the inner and outer rings of the bearing. And to prevent the leakage of the lubricating medium and the entry of dust into the reducer, a rotary seal two 28 is arranged between the external gear ring 11 and the follower cover 22, and axial limit is carried out through a snap ring for hole three 29. Threaded holes are evenly opened at the bottom end of the external gear ring 11 in the axial direction and are connected to the input end of the robot joint through fasteners. The number and size of the threaded holes are opened according to requirements, and no further requirements are made in this embodiment.

[0061] Specifically, a cover one 30 is arranged at the top end of the external gear ring 11, and the two are fastened by bolts one 31. An O-ring one 32 is arranged between the cover one 30 and the external gear ring 11 for sealing. Here, the O-ring can also be replaced with a sealing element such as a gasket according to requirements, and the specific sealing form can meet the sealing requirements; a bearing seat with a chute is arranged at the center of the cover one 30 to support the tapered roller bearing one 15. An axial sliding block 33, a wave spring 34 and a pre-tightening screw cap 35 are sequentially arranged on the upper surface of the bearing seat. By screwing the pre-tightening screw cap 35 to compress the wave spring 34 to generate an axial load, the sliding block is pushed to axially move along the chute of the bearing seat, and the sliding block applies a pre-pressure to the outer ring of the tapered roller bearing one 15, thereby forcing the sun bevel gear shaft 77 to generate an axial micro-displacement, and the pre-tightening force can be adjusted in real time according to the load. The tapered roller bearing one 15, the tapered roller bearing two 16 and the tapered roller bearing three 19 on the sun bevel gear shaft 7 all adopt adjustable clearance bearings.

[0062] Specifically, to compress the transmission shaft 10 in space, two windows are oppositely opened at the top end of the cover one 30 to make the meshing surface of the end face spiral bevel gear 2 protrude. Cover two 36 are respectively installed on the two windows and are fastened by bolts two 37. An O-ring two 38 is arranged between the cover two 36 and the cover one 30 for sealing.

[0063] Specifically, a channel is integrally cast on the side surface of the cover two 36 to cover the hyperbolic spiral bevel gear shaft 1 and the motor shaft. The direction of the channel is arranged in a staggered manner to save the installation space of the reducer. Motor mounting holes are arranged at the end of the channel, and the servo motor 4 is fastened by bolts three 39. An O-ring three 40 is arranged between the motor and the cover two 36 for sealing.

[0064] Combined Figure 7 , the working principle of the high-rigidity robot joint reducer device will be described in detail.

[0065] The robot joint reducer device has a three-stage reduction drive, including a first-stage reduction drive, a second-stage reduction drive, and a third-stage reduction drive. During the installation of the reducer, a lubricating medium is filled inside. The seals in the reducer can effectively prevent the leakage of the medium and the intrusion of impurities. The type of lubricating medium is selected according to actual usage requirements and is not specifically defined here.

[0066] Among them, the first-stage reduction drive structure adopts two sets of spiral bevel gears arranged at 90° vertically, and are respectively input in parallel through two servo motors 4. The transmission ratio can reach 1:1 to 1:5. During the operation of the reducer, according to the output requirements of the robot joint load end, the servo motor 4 can be divided into motor A to output a positive driving torque T 1 , and motor B applies a reverse preloading torque T 2 = (0.05 - 0.1)T1, so that the reverse tooth surface of the spiral bevel gear driven by motor B is always continuously pressed. When the reducer changes direction, the torque vector active control algorithm is used to adjust the torque directions and magnitudes of the two motors in real time, so that the gear meshing surface maintains a constant preloading contact under alternating loads, realizing zero backlash during the first-stage reduction drive process.

[0067] The second-stage reduction drive structure adopts a parallel spur gear drive, and the transmission ratio can reach 1:5 to 1:20. Torque is input to the spur gear 5 through the spur gear shaft 6 fixedly connected to two sets of end face spiral bevel gears 2. Since the torque directions output by the first-stage reduction drive are opposite, the tooth surfaces meshing between the spur gear shaft 6 and the spur gear 5 always maintain two-way fitting, thereby realizing zero backlash during the second-stage reduction drive process.

[0068] The third-stage reduction drive structure adopts a helical planetary gear drive, and the transmission ratio can reach 1:1 to 1:5. The planetary gears are driven by two sets of parallel planetary gear sets. Except for the opposite helix angle directions of the two sets of gears, the other parameters are the same. The number of each set of planetary gears depends on the design load of the transmission. Usually, there are three or four. The more the number, the greater the load borne. There are no specific requirements in this embodiment. The transmission method is to drive the planetary gears through the sun helical gear shaft 7 fixedly connected to the spur gear 5, and the outer gear ring 1111 is a fixed part. The outer ring of the tapered roller bearing 15 at the top of the sun helical gear shaft 7 has a clearance fit with the end cover 30. The bearing seat end face is machined with a chute, and an axial sliding block 33 is arranged in the chute to squeeze the bearing outer ring for axial sliding, thereby driving the sun helical gear shaft 7 to generate an axial micro-displacement. A corrugated spring is arranged at the top of the axial sliding block 33 to dynamically compensate for the axial play caused by torque mutation or tooth surface wear. The axial thrust of the sun helical gear shaft 7 causes the two sets of planetary gears with opposite helix angle directions to generate equal and opposite angular displacements, so that there is always a planetary gear set in contact with the tooth surface of the sun helical gear shaft 7 during the alternating process of the reducer torque output direction, thereby realizing zero backlash during the third-stage reduction drive process.

[0069] In this embodiment, multi-stage compound backlash elimination is adopted to achieve high-rigidity transmission of the joint reducer. The total transmission ratio ranges from 1:5 to 1:500, which can meet the usage requirements of most robot joints. Among them, the first-stage and second-stage reduction transmissions use the electrical backlash elimination method to dynamically adjust the output torque of the motor and actively eliminate the gear backlash. The third-stage reduction transmission uses the mechanical backlash elimination method to passively eliminate the gear backlash by utilizing the structural characteristics of helical gear meshing.

[0070] Embodiment 2

[0071] In another typical embodiment of the present invention, as Figures 1-7 shown, a working method of a robot joint reducer device is given, and the construction is the same as that of the robot joint reducer device in Embodiment 1.

[0072] A working method of a robot joint reducer device includes:

[0073] The follower cover 22 is connected to an external actuator.

[0074] During movement, one driving element serves as the main driving element to output a positive driving torque, and the other driving element serves as the auxiliary driving element to output a reverse torque, which is less than the positive driving torque, so as to keep the reverse tooth surfaces of the first-stage driven bevel gear and the first-stage driving bevel gear engaged, and at the same time ensure that the reverse tooth surfaces of the second-stage driving gear and the second-stage driven gear are engaged, eliminating the backlash of the first-stage reduction transmission and the second-stage reduction transmission.

[0075] The sun helical gear shaft 7 generates an axial displacement, driving two sets of planetary gear sets with opposite helix directions to rotate in opposite angles, so that the sun helical gears on the sun helical gear shaft 7 are respectively in close contact with the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the backlash of the third-stage reduction transmission.

[0076] The driving element drives the follower cover 22 to output power after passing through the first-stage reduction transmission, the second-stage reduction transmission, and the third-stage reduction transmission in sequence.

[0077] Adjust the pre-tightening force of the axial elastic mechanism so that the sun helical gear shaft 7 can be engaged with the opposite tooth surfaces of the two sets of planetary gear sets at the same time. In the reducer, the sun helical gear shaft 7 applies an axial pre-tightening force through a corrugated spring. Combining the adjustable clearance characteristics of the tapered roller bearing, the gap expansion caused by tooth surface wear can be dynamically compensated, improving the working stability of the robot joint reducer.

[0078] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A robot joint reducer device, characterized in that: include: The three-stage reduction transmission is a helical planetary gear structure. Two sets of planetary gear sets with opposite rotation directions are installed on the planet carrier, and they are respectively meshed with the sun helical gear shaft. The end of the sun helical gear shaft is equipped with an axial elastic mechanism to apply axial elastic preload to the sun helical gear shaft to eliminate the return clearance of the three-stage reduction transmission; the planet carrier is connected to a follower cover as the output end; A two-stage reduction transmission, comprising a two-stage driven gear and a two-stage driving gear, wherein the two-stage driven gear is mounted on the sun helical gear shaft and rotates at a constant angular velocity, and two two-stage driving gears respectively mesh with the two-stage driven gears; The primary reduction transmission is provided with two groups of matched secondary driving gears. Each group of primary reduction transmission includes meshing primary driving bevel gears and primary driven bevel gears. The primary driven bevel gears rotate coaxially with the secondary driving gears at the same angular velocity. The primary driving bevel gears are connected to the driving elements. The two driving elements apply reverse torque to the secondary driven gears through the secondary driving gears to eliminate the return clearance between the primary reduction transmission and the secondary reduction transmission.

2. The robot joint reducer device according to claim 1, characterized in that: The primary driving bevel gear is a hyperbolic spiral bevel gear shaft, the primary driven bevel gear is an end face spiral bevel gear, and the driving element is located outside one end of the secondary driven gear and is distributed toward the axis of the sun bevel gear shaft.

3. The robot joint reducer device according to claim 2, characterized in that: The two secondary driving gears are arranged symmetrically relative to the axis of the sun bevel gear shaft.

4. The robot joint reducer device according to claim 2 or 3, characterized in that: The axes of the primary driving bevel gears connected to the two driving elements are parallel and the axes of the primary driving bevel gears and the primary driven bevel gears in the same group are perpendicular.

5. The robot joint reducer device according to claim 1, characterized in that: The three-stage reduction transmission also includes an outer ring gear that matches the planetary gear set, and the outer ring gear is connected to an end cover. One end of the sun bevel gear shaft rotates to match the end cover, and the other end rotates to match the follower cover. An axial movement allowance is left between the sun bevel gear shaft and the planetary gear set.

6. The robot joint reducer device according to claim 5, characterized in that: The axial elastic mechanism includes an axial sliding block, a wave spring and a pre-tightening nut cover. The sun helical gear shaft passes through a tapered roller bearing and a matching end cover. The axial sliding block abuts against an outer ring of the tapered roller bearing. The pre-tightening nut cover matches the end cover. The wave spring abuts between the pre-tightening nut cover and the axial sliding block.

7. The robot joint reducer device according to claim 1, characterized in that: The planet carrier comprises a transmission shaft, a planetary gear set is mounted on the transmission shaft, and the planetary gear set meshes with an outer gear ring.

8. The robot joint reducer device according to claim 7, characterized in that: The planet carrier also includes a planet carrier 1 and a planet carrier 2 which are axially spaced and distributed along the sun bevel gear shaft, wherein one set of planetary gear sets is located between the planet carrier 1 and the planet carrier 2, and another set of planetary gear sets is located between the planet carrier 2 and the follower cover.

9. A method for operating a robot joint reducer device, comprising: constructing a robot joint reducer device as claimed in any one of claims 1 to 8, characterized in that: include: The follower cover is connected to the external actuator; During movement, one driving element outputs a positive driving torque as the main driving element, and the other driving element outputs a reverse torque as the auxiliary driving element, which is smaller than the positive driving torque, so as to keep the reverse tooth surface of the first-stage driven bevel gear meshing with the first-stage driving bevel gear, and at the same time ensure the reverse tooth surface of the second-stage driving gear and the second-stage driven gear meshing, thereby eliminating the return clearance between the first-stage reduction transmission and the second-stage reduction transmission; The sun bevel gear shaft produces axial displacement, driving the two sets of planetary gear sets with opposite rotation directions to rotate at opposite angles, so that the sun bevel gears on the sun bevel gear shaft are respectively close to the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the return clearance of the three-stage reduction transmission; the driving element drives the follower cover to output power after passing through the first-stage reduction transmission, the second-stage reduction transmission and the third-stage reduction transmission in sequence.

10. The working method of the robot joint reducer device according to claim 9, characterized in that: The preload force of the axial elastic mechanism is adjusted so that the sun helical gear shaft can mesh with the opposite tooth surfaces of the two sets of planetary gear sets at the same time.

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